Baseline living‐donor kidney volume and function associate with 1‐year post‐nephrectomy kidney function

Abstract

Living donors may develop kidney dysfunction more often than equally healthy populations. The purpose of this study was to determine whether computed tomography‐assessed remaining kidney volume indexed to body surface area (RKV/BSA) was associated with 1‐year post‐nephrectomy renal function independent of baseline renal function. Using multivariable regression, we modeled 1‐year estimated glomerular filtration rate (eGFR) and eGFR <60 mL /min/1.73 m2 and considered pre‐determined baseline eGFR subgroups in 151 consecutive donors. Mean ± SD baseline age, eGFR, RKV, BSA, and RKV/BSA were 38 ± 11 years, 97 ± 16 mL/min/1.73 m2, 153 ± 29 mL, 1.9 ± 0.2 m2, and 80.0 ± 12.8 ml/m2, respectively; 50% were female and 94% were white. Mean baseline eGFR was greater with increasing RKV/BSA tertiles (92 ± 14, 97 ± 16, 107 ± 16 mL/min/1.73 m2; P < 0.001). Post‐nephrectomy eGFR remained separated by RKV/BSA tertiles. At baseline, each SD greater RKV/BSA and eGFR was independently associated with higher adjusted 1‐year eGFR by 2.4 and 9.2 mL/min/1.73 m2. Each SD greater age associated with 2.2 mL/min/1.73 m2 lower adjusted 1‐year eGFR. Adjusted odds of 1‐year eGFR <60 increased significantly for donors with RKV/BSA <80 mL/m2. With baseline eGFR <90, probability of 1‐year eGFR <60 increased to >80% with decreasing RKV/BSA values below 80 mL/m2. Those with baseline eGFR >100 rarely developed 1‐year eGFR <60 if RKV/BSA remained >60 mL/m2. RKV/BSA independently associated with 1‐year eGFR <60, especially with lower baseline eGFRs. Additional studies should evaluate the predictive utility of this measure and its potential role in donor evaluations and informed consent.

Remaining kidney volume indexed to weight as a strong predictor of estimated glomerular filtration rate at 1 year and mid‐term renal function after living‐donor nephrectomy ‐ a retrospective observational study

“…In this study, we showed that RKV was independently correlated with eGFR before (r = 0.151, P = 0.035) and after 1 year of donation (r = 0.171, P = 0.017). We also found that RKV, adjusted to donor's weight and predonation eGFR (described as “volume dose” [15]), had positive and strong correlation with eGFR one year after donation, agreeing with most recent series [14,16,23]. A larger mass of nephrons remaining adjusted to donor's weight seems to predict a better long‐term eGFR.…”

“…Being overconcerned with the target eGFR < 60 ml/min/1.73 m 2 after donation, without taking into account other factors could have unintended and detrimental consequences in selecting transplant candidates. In fact, there has been considerable debate over whether it is justifiable to consider or not healthy kidney donors with isolated eGFR values below 60 ml/min/1.73 m 2 as having chronic kidney disease (CKD) or vice versa [14,16,26]. Considering this, in our cohort, we showed that having predonation eGFR < 90 ml/min/1.73 m 2 is associated with a stronger trend towards an eGFR 1 year after donation < 60 ml/min/1.73 m 2 , particularly in male donors with a ratio of RKV/W bellow 2.51 cm 2 /kg (Fig.…”

“…Kidney volume as a surrogate marker of nephron mass and renal function has been presented by many authors as a good predictor of recipient renal function. Many studies to date have investigated donor factors associated with recipient renal function and outcomes, though scarce data are available about factors associated with donor's renal function after nephrectomy [9‐16].…”

The impact of measuring split kidney function on post-donation kidney function: A retrospective cohort study

“…The impact of measuring split kidney function on post-donation kidney function: A retrospective cohort study Our study differs from other studies that found stronger prediction of post-donation eGFR [9][10][11]. The reason for this difference may relate to our longer follow up time while prior studies examined eGFR at only 6 to 12 months [9][10][11].…”

“…split kidney function) only in patients with a difference in kidney length exceeding 1 cm on CT [7,8]. However, it is unclear if this method alone should be adopted by all individual donor programs given the lack of long term data on their ability to predict post-donation remaining kidney function [9][10][11][12][13][14]. This is of particular concern for donors with a clinically significant difference in split kidney function on renography that is missed on CT and donors with low eGFR after donation.…”